The present invention relates to a method and delivery device for delivering a substance, such as a drug or pharmaceutical agent transdermally to a patient. More particularly, the invention is directed to a device containing a diluent for delivering a reconstituted drug transdermally to a patient.
Various devices have been proposed for transdermally delivering pharmaceutical agents, drugs and other substances. Although the subcutaneous delivery methods using a standard cannula are effective for many applications, the pain normally induced by the cannula has prompted the development of less painful delivery methods.
The use of prefilled syringes and other delivery devices has increased significantly in recent years due in part to the convenience and reduced risk of contamination. Prefilled syringes are generally suitable for drug solutions that are stable for extended periods of time. The drug solution itself must be stable and the solution must not interact with the syringe barrel or other container during storage. Certain drugs are inherently unstable in solution and are normally stored as a dried or lyophilized powder that must be reconstituted prior to use. These drugs are not suitable for standard prefilled syringes.
A method that has received much attention in recent years is the delivery of drugs through the skin by forming micropores or cuts through the stratum corneum. By penetrating the stratum corneum and delivering the drug to the skin in or below the stratum corneum, many drugs can be effectively administered. The devices for penetrating the stratum corneum generally include a plurality of micron size needles or blades having a length to penetrate the stratum corneum without passing completely through the epidermis. Examples of these devices are disclosed in U.S. Pat. No. 5,879,326 to Godshall et al.; U.S. Pat. No. 5,250,023 to Lee et al., and WO 97/48440.
The skin is made up of several layers with the upper composite layer being the epithelial layer. The outermost layer of the skin is the stratum corneum which has well known barrier properties to prevent molecules and various substances from entering the body and analytes from exiting the body. The stratum corneum is a complex structure of compacted keratinized cell remnants having a thickness of about10-30 microns.
The natural impermeability of the stratum corneum prevents the administration of most pharmaceutical agents and other substances through the skin. Numerous methods and devices have been proposed to enhance the permeability of the skin and to increase the diffusion of various drugs through the skin so that the drugs can be utilized by the body. Typically, the delivery of drugs through the skin is enhanced by either increasing the permeability of the skin or increasing the force or energy used to direct the drug through the skin.
One example of a method for increasing the force for the delivery of drugs through the skin include iontophoresis. Iontophoresis generally applies an external electrical field to ionize the drug, thereby increasing the diffusion of the drug through the skin. However, it can be difficult to control the amount and rate of drug delivery using iontophoresis. Under some circumstances, iontophoresis can cause skin damage depending on the extent of ionization, the energy applied to ionize the drug and duration of the treatment.
Sonic, and particularly ultrasonic energy, has also been used to increase the diffusion of drugs through the skin. The sonic energy is typically generated by passing an electrical current through a piezoelectric crystal or other suitable electromechanical device. Although numerous efforts to enhance drug delivery using sonic energy have been proposed, the results generally show a low rate of drug delivery.
The prior methods and apparatus for the transdermal administration of drugs has exhibited limited success. Accordingly, a continuing need exists in the industry for an improved device for the administration of various drugs and other substances.
The present invention is directed to a method and device for the transdermal delivery of a substance, such as a drug, vaccine or other pharmaceutical agent, to a patient. In particular, the invention is directed to a method and device for delivering a pharmaceutical agent to the stratum corneum of the skin to a sufficient depth where the pharmaceutical agent can be absorbed and utilized by the body.
Accordingly, a primary object of the invention is to provide a method and device for reconstituting a pharmaceutical agent and administering the pharmaceutical agent transdermally through the skin substantially without pain to the patient.
Another object of the invention is to provide a prefilled delivery device having a reservoir containing a substance and a plurality of microneedles or blades for penetrating the stratum corneum of the skin for delivering the substance to the skin.
A further object of the invention is to provide a device having a dried pharmaceutical agent and a reservoir containing a diluent for reconstituting the dried pharmaceutical agent and delivering the pharmaceutical agent to the patient.
Another object of the invention is to provide a device having a bladder containing a substance and a cannula for piercing the bladder to dispense the substance and deliver the substance to the patient.
A further object of the invention is to provide a device for the transdermal delivery of a substance where the apparatus includes a bladder containing the substance, a cannula to pierce the bladder and a protecting shield to prevent premature piercing of the bladder.
A still further object of the invention is to provide a device for the transdermal delivery of a pharmaceutical agent having a plurality of microneedles for penetrating the stratum corneum and a bladder containing the pharmaceutical agent for delivering the pharmaceutical agent to the microneedles.
Another object of the invention is to provide a device having a plurality of microneedles for penetrating the stratum corneum and an outer adhesive patch for adhesively attaching the apparatus to the skin of a patient.
Still another object of the invention is to provide a transdermal delivery device having an array of microneedles for penetrating the stratum corneum of the skin, a flexible bladder containing a substance and flexible cover that can be deflected toward the bladder to dispense the substance to the microneedles.
A further object of the invention is to provide a device for the transdermal delivery of a substance to a patient where the device has an array of microneedles and a dried substance on the microneedles, where the dried substance is reconstituted by dispensing a diluent from a bladder within the device.
These and other objects of the invention are substantially attained by providing an intradermal delivery device for introducing a substance into the skin of a patient. The device comprises a housing having a central opening and a planar member positioned in the central opening of the housing. The planar member has an inner surface and an outer surface. The outer surface has a plurality of microneedles extending therefrom, at least one opening passing through the planar member from the inner surface to the outer surface, and at least one cannula on the inner surface. A flexible cover is coupled to the housing and overlies the central opening and is spaced from the planar member to define a cavity in the housing. A bladder containing at least one substance is positioned in the cavity of the housing between the planar member and the flexible cover. The bladder is piercable by the cannula and is collapsible by pressing the flexible cover to dispense the substance through the opening to the microneedles.
The objects and advantages of the invention are further attained by providing an intradermal device for administering a pharmaceutical agent through the skin of a patient. The device comprises a housing having a bottom wall and at least one side wall defining a cavity. The bottom wall has a plurality of microneedles and a plurality of passages extending through the bottom wall to the microneedles. A flexible cover is coupled to the housing and encloses the cavity. The flexible cover has a generally arcuate shaped outer surface in a first position and is movable from the first position to a second position toward the bottom wall. A bladder contains a substance and the bladder is positioned in the cavity and is collapsible by applying pressure to the flexible cover to dispense the substance through the passages in the bottom wall to the microneedles.
Another object of the invention is to provide a method of administering a substance such as a pharmaceutical agent through the skin of a patient which comprises providing a delivery device having a housing with a bottom wall and at least one side wall defining a cavity. The bottom wall has an outer surface with a plurality of microneedles extending therefrom and has a plurality of passages extending through the bottom wall from the cavity to the microneedles. A bladder contains at least one substance and is positioned in the cavity, and a flexible cover encloses the cavity. The device contacts the skin of a patient and sufficient pressure is applied to the device to cause the microneedles to penetrate the skin a sufficient depth for delivering a substance to the patient. Sufficient pressure is applied to the flexible cover to rupture the bladder and dispense the substance to the microneedles.
The objects, advantages and other salient features of the invention will become apparent from the following detailed description which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.